I just replaced the head gaskets on my 97 Blazer. Went to start it and nothing. No lights or any electrical power. Shifter is stuck in park and the key is stuck in the ignition. Tested the battery. It was bad. Installed new battery, same condition.

 

So I found the problem. There is a black wire near the alternator. I thought it was a ground. Turns out it needs to connect to the alt. hot. Hooked it up and got power. Truck started right up.

 

Happens to the best of us. Glad you fixed it!